Method to recover high molecular weight poly(arylene sulfide) by reprecipitation

ABSTRACT

In one embodiment, the inventive process comprises: (a) preparing a first slurry comprising a first particulate PAS resin and a polar organic compound, (b) heating the first slurry to a temperature in the range of about 20° C. (68° F.) to about 40° C. (104° F.) below the liquid-to-solid phase transitional temperature of the first particulate resin, and (c) rapidly cooling the first slurry to below about 50° C. (122° F.) below the liquid-to-solid phase transitional temperature of the first particulate resin in the polar organic compound to form a second slurry, comprising the polar organic compound and a polymeric mixture comprising a novel particulate high molecular weight PAS resin and a minor amount of a particulate low molecular weight PAS resin. 
     In another embodiment, the inventive process comprises: (a) preparing a liquid mixture comprising a first particulate PAS resin and a polar organic compound, at a temperature above the solid-to-liquid phase transitional temperature of the first particulate resin, (b) slowly cooling the liquid mixture to between about 20° C. (68° F.) to about 40° C. (104° F.) below the liquid-to-solid phase transitional temperature of the first particulate PAS in the polar organic compound resin to form a first slurry comprising the polar organic compound and a second particulate PAS resin, and (c) rapidly cooling the first slurry to about 50° C. (122° F.) below the liquid-to-solid phase transitional temperature of the first particulate resin in the polar organic compound, thus forming a second slurry comprising the polar organic compound and a polymeric mixture comprising a third particulate high molecular weight resin, wherein third particulate resin, when recovered has a higher molecular weight than its respective first and second particulate resins, if recovered by conventional means.

FIELD OF THE INVENTION

This invention relates to a process for the production of poly(arylenesulfide). In one aspect, this invention relates to a process ofproducing and recovering high molecular weight poly(arylene sulfide).

BACKGROUND OF THE INVENTION

In applications such as in the production of fibers and films fromarylene sulfide polymers, moderately branched to linear poly(arylenesulfide) resins, henceforth PAS, are often preferred over branchedtypes. Furthermore, it is desirable that these moderately branched tolinear PAS resins have as high a molecular weight as possible in orderto meet specialized product requirements.

While high molecular weight branched PAS resins can readily be producedby the addition of branching agents (e.g., trichlorobenzene) to thepolymerization process, moderately branched to linear, high molecularweight PAS resins cannot be made by this method. Previous methods toproduce high molecular weight PAS resins without the use of branchingagents include air curing the polymer, extracting the low molecularweight fractions from the polymer, and using reaction modifying agents(e.g., alkali metal carboxylates) in the polymerization process. Whilethese previous methods proved to be successful, there exist certain costand/or physical limitations associated therewith which would not makethem available to some who desire moderately branched to linear, highermolecular weight PAS resins. Therefore, it would be beneficial if animproved method of preparation could be devised which results in amoderately branched to linear, high molecular weight PAS.

Linear and non-linear PAS resins can be produced by various processesusing polyhalo-substituted aromatic compounds (e.g., dihalobenzenes,trihalobenzenes, dihalobenzophenones and dihaloaromatic sulfones). Afterthe PAS resin is polymerized, the particulate PAS resin must berecovered from the polymerization reaction mixture. There are severalconventional means for recovering linear and non-linear PAS resins froma completed polymerization reaction mixture such as, for example,flashing the liquid reaction media or a recovery process referred to asa liquid quench process such as that described in U.S. Pat. No.4,415,729.

In the liquid quench process, a waste product often referred to as"slime" is produced. This slime generally comprises low molecular weightPAS fines. While the liquid quench process does separate some of thisslime material from the more useful, higher molecular weight polymericmaterial, this separation is not complete. If this slime material (i.e.,low molecular weight PAS fines) is not separated from the more useful,higher molecular weight polymeric material, this will result in loweringthe molecular weight of the final recovered polymeric product.Therefore, one object of this invention is to provide a process foreffectively separating the lower molecular weight polymeric material.This inventive separation process results in substantially increasingthe molecular weight of the final recovered polymeric product.

Other aspects, concepts, and objects of this invention will becomeapparent from the following Detailed Description when considered withthe appended claims.

SUMMARY OF THE INVENTION

This invention provides a process for producing and recovering improvedhigh molecular weight PAS resins.

In accordance with one embodiment, the inventive process comprises: (a)preparing a first slurry, wherein the solid component thereof comprisesa first particulate PAS resin, and wherein the liquid component thereofcomprises a polar organic compound, (b) heating the first slurry to atemperature in the range of about 20° C. (68° F.) to about 40° C. (104°F.) below the liquid-to-solid phase transitional temperature of thefirst particulate PAS resin in the polar organic compound, and (c)rapidly cooling the heated first slurry to a temperature below about 50°C. (122° F.) below the liquid-to-solid phase transitional temperature ofthe first particulate PAS resin in the polar organic compound to form asecond slurry, wherein the liquid component thereof comprises the polarorganic compound and wherein the solid component thereof comprises aparticulate polymeric mixture comprising a novel particulate highmolecular weight PAS resin and a minor amount of particulate lowmolecular weight PAS resin, such that the final recovered PAS resin hasa higher molecular weight than its respective first particulate resinwould if recovered by conventional means.

In accordance with another embodiment, the inventive process comprises:(a) preparing a heated liquid mixture comprising a first particulate PASresin in a liquid phase and a polar organic compound, wherein thetemperature of the liquid mixture is above the solid-to-liquid phasetransitional temperature of the first particulate PAS resin in the polarorganic compound, (b) slowly cooling the liquid mixture to a temperatureabout 20° C. (68° F.) to about 40° C. (72° F.) below the liquid-to-solidphase transitional temperature of the first particulate PAS resin in thepolar organic compound, to form a first slurry, wherein the liquidcomponent thereof comprises the polar organic compound, and wherein thesolid component thereof comprises a second particulate high molecularweight PAS resin, and (c) rapidly cooling the first slurry to atemperature of about 50° C. (122° F.) below the liquid-to-solid phasetransitional temperature of the first particulate PAS resin in the polarorganic compound to form a second slurry, wherein the liquid componentthereof comprises the polar organic compound, and wherein the solidcomponent thereof comprises a third particulate polymeric mixturecomprising the novel particulate high molecular weight PAS resin and aminor amount of particulate low molecular weight PAS resin, such thatthe final recovered PAS resin has a higher molecular weight than itsrespective first and second particulate resins would if recovered byconventional means.

The novel particulate high molecular weight PAS resin prepared inaccordance with this invention has a higher molecular weight than itsrespective first particulate PAS resin would, if recovered byconventional means. The low molecular weight PAS resin resulting fromthis inventive process has a lower molecular weight than the firstparticulate PAS resin would, if recovered by conventional means. Thus,the high molecular weight PAS resin component can readily be separatedfrom the low molecular weight PAS resin component in order to obtain thefinal product exhibiting the higher molecular weight.

DETAILED DESCRIPTION OF THE INVENTION

This invention is useful with particulate PAS resins regardless of theirmethod of preparation. Generally, the PAS resins treated in accordancewith this invention are phenylene sulfide polymers. Specifically, thisinvention can be employed to increase the molecular weight of a PASresin by separating out the lower molecular weight resin constituenttherefrom.

In general, the PAS resins treated by this invention can be produced bycontacting a polyhaloaromatic compound with a sulfur source and a polarorganic compound under polymerization conditions. Optionally, componentssuch as polyhaloaromatic compounds having more than two halogensubstitutes per molecule, and/or polymerization modifying compounds(e.g., alkali metal carboxylates and/or lithium halides) can also beadded to the polymerization process.

Examples of PAS resins which can be treated in accordance with thisinvention include, but are not limited to, poly(arylene sulfides),poly(arylene sulfide ketones), poly(arylene sulfide diketones),poly(biarylene sulfides) and poly(arylene sulfide sulfones). The"arylene" group of the above PAS resin examples is preferably aphenylene group.

Although other polymeric resins are not excluded, in general, the PASresins most apt to be treated in accordance with this invention can berepresented by having as the repeating unit: ##STR1##

According to the present invention, the molecular weight of a PAS resinis determined by measuring the resin's melt flow rate. A high melt flowrate is indicative of a lower molecular weight PAS resin and vice versa.

As used herein, the terms "melt flow" and/or "flow rate" are usedinterchangeably and refer to the rate at which a melted PAS resin flowsthrough an orifice, having a specific diameter and length, whensubjected to a specific downward pressure. Melt flow values are recordedin units of grams of extrudate which have flowed through the orificeover a ten minute interval (g/10 min) and are determined by a modifiedversion of ASTM D1238, Procedure B, Condition X/5.0, where X is aspecific temperature which depends on the particular PAS resin beingtested. For example, for polyphenylene sulfide resin, X is 315° C. Themodification employed herein is that the initial preheating time is 5minutes, as opposed to the minimum 6 minute period specified by ASTMD1238, Procedure B.

The invention provides a process for producing and recovering improvedhigh molecular weight PAS resins. Since the embodiments of thisinvention can be practiced at any time after a PAS resin is polymerized,it can be viewed as either (1) an effective means for providing a PASresin having associated therewith increased molecular weight, or (2) ameans for isolating an increased molecular weight fraction of apreviously prepared PAS resin.

When practicing the first embodiment of this invention, a first slurryis prepared wherein the solid component thereof comprises a firstparticulate PAS resin, and wherein the liquid component thereofcomprises a polar organic compound. Any suitable method can be employedto prepare this first slurry. An example of suitable method which willproduce such a first slurry is one wherein a polyhalo-substitutedaromatic compound is contacted under suitable polymerization conditionswith reactants comprising a sulfur source, a polar organic compound andwater, to produce a polymer containing polymerization reaction mixture.Depending upon the type of polymer prepared, this reaction mixture canbe either (a) a liquid mixture, comprising a particulate PAS resin in aliquid phase, a polar organic compound, water, unreacted monomer andvarious liquid by-product materials or (b) a slurry, wherein the solidcomponent thereof comprises a particulate PAS resin, and wherein theliquid component thereof comprises a polar organic compound, water,unreacted monomer and various liquid by-product materials.

When practicing the first embodiment of this invention, if the firstslurry is prepared from a completed PAS polymerization process, andfurther if the reaction mixture of this completed polymerization processis a liquid mixture wherein the particulate PAS resin is in a liquidphase, the temperature of this liquid mixture must be lowered to belowthe liquid-to-solid phase transitional temperature of the liquid-phasePAS resin contained therein. Under these conditions, a first slurryresults, wherein the solid component thereof comprises a firstparticulate PAS resin, and wherein the liquid component thereofcomprises a polar organic compound, water, unreacted monomer and variousliquid by-product materials.

The phase "liquid-to-solid phase transitional temperature," as usedherein, refers to the temperature at which a liquid mixture comprising aliquid-phase PAS resin must be lowered in order to solidify theliquid-phase PAS resin.

While the liquid-to-solid phase transitional temperature differs withthe type of PAS resin produced and with the concentration and nature ofthe remaining liquid constituents in contact therewith, it can readilydetermined by one of ordinary skill in the art. For example, by using ahigh pressure, flat glass gage that can be heated, such as thatavailable from the Jerguson Gage & Valve Co., it can be seen thatpoly(phenylene sulfide), when in the presence of the polar organiccompound NMP, has a liquid-to-solid phase transitional temperature ofabout 230° C. (446° F.). Therefore, in order to solidify a liquid-phasepoly(phenylene sulfide) present in a liquid mixture also comprising NMP,the temperature of a liquid mixture must be lowered to below about 230°C. (446° F.).

Poly(phenylene sulfide ketone) has a liquid-to-solid phase transitionaltemperature of about 245° C. (473° F.) when in the presence of the polarorganic compound NMP. Therefore, in order to solidify a liquid-phasepoly(phenylene sulfide ketone) present in a liquid mixture alsocomprising NMP, the temperature of a liquid mixture must be lowered tobelow about 245° C. (473° F.).

Poly(phenylene sulfide diketone) has a liquid-to-solid phasetransitional temperature of about 302° C. (576° F.), when in thepresence of the polar organic compound NMP. Therefore, in order tosolidify a liquid-phase poly(phenylene sulfide diketone) present in aliquid mixture also comprising NMP, the temperature of a liquid mixturemust be lowered to below about 302° C. (576° F.).

Another example of a suitable method which results in such a firstslurry comprises taking a particulate PAS resin which has already beenprepared, recovered, and optionally dried, and adding this particulateresin to a liquid mixture comprising a polar organic compound.

In the first slurry employed in the first embodiment of this invention,the molar ratio of the moles of solvent per moles of divalent sulfurpresent in the first particulate PAS resin is generally determined bymechanical and/or economic limitations. Preferably, in the first slurry,the molar ratio of the moles of polar organic compound to the moles ofdivalent sulfur present in the first particulate resin ranges from about3:1 to about 25:1; more preferably, from about 6:1 to about 20:1; andeven more preferably, from about 8:1 to about 16:1.

The moles of divalent sulfur present in the first particulate PAS resincan be readily determined by one of ordinary skill in the art. Forexample, if the heated first slurry which contains the first particulatePAS resin is the slurry which results at the termination of a typicalpolymerization reaction, the moles of divalent sulfur present in the PASresin are approximately equal to the moles of sulfur charged to thepolymerization vessel.

The polar organic compounds useful when practicing this invention arepolar organic compounds which those of ordinary skill in the art employin the polymerization processes of PAS resins. Examples of such polarorganic compounds include, but are not limited to,hexamethylphosphoramide, tetramethylurea, N,N'-ethylenedipyrrolidone,N-methyl-2-pyrrolidone (NMP), pyrrolidone, caprolactam,N-ethylcaprolactam, sulfolane, N,N'-dimethylacetamide, low molecularweight polyamides, and mixtures thereof. The presently preferred polarorganic compound for practicing this invention is NMP.

If treating the PAS resin in accordance with the first embodiment ofthis invention, after the first slurry is prepared, the slurry is heatedto a temperature in the range of about 20° C. (68° F.) to about 40° C.(104° F.) below the liquid-to-solid phase transitional temperature ofthe first particulate PAS resin contained therein. The time for whichthe first slurry should be held within this temperature range depends inpart on the treating temperature employed, the concentration of thelower molecular weight PAS resin in the first particulate PAS resin, andthe desired concentration of lower molecular weight PAS resin in thenovel particulate high molecular weight PAS resin. The hold period ofthe first slurry in the appropriate temperature range generally rangesfrom about 5 seconds to about 8 hours, preferably from about 10 secondsto about 4 hours.

After the first slurry is heated to the appropriate elevated temperatureand held at that temperature for the appropriate period of time, thetemperature of this first slurry is rapidly lowered to a temperature ofabout 50° C. (122° F.) below the liquid-to-solid phase transitionaltemperature of the first particulate resin in the polar organiccompound. Preferably, the temperature of this first slurry is rapidlylowered to a temperature of about 75° C. (167° F.) below theliquid-to-solid phase transitional temperature of the first particulateresin.

The term "rapid lowering of the temperature" is meant to describe areduction in temperature that is achieved by applying a cooling means tothe contents of the reactor, as opposed to allowing the reactor contentsto cool undisturbed. One of ordinary skill in the art may choose anyconvenient means to achieve such cooling, such as, for example, applyingcooling water to the reactor. Generally, this cooling of the heatedfirst slurry will occur at a rate greater than about 1° C. (1.8°F.)/minute.

The rapid cooling of the heated first slurry to a temperature of about50° C. (122° F.) below the liquid-to-solid phase transitionaltemperature of the first particulate resin contained therein results inthe formation of a second slurry, wherein the liquid component thereofcomprises a polar organic compound and wherein the solid componentthereof comprises a particulate polymeric mixture comprising a novelparticulate high molecular weight PAS resin and a minor amount ofparticulate low molecular weight PAS resin.

Because of the difference in particle size of the low molecular weightand high molecular weight PAS resins present in the particulatepolymeric mixture produced, the high molecular weight resin can beseparated from the low molecular weight resin by, for example,filtration through an appropriately chosen filtration means.

When practicing the second embodiment of this invention, a heated liquidmixture comprising a first particulate PAS resin in a liquid-phase and apolar organic compound is prepared. This liquid mixture is at anelevated temperature which is sufficient to maintain the PAS resincontained therein in a liquid-phase.

Any suitable method can be employed to prepare this heated liquidmixture. An example of suitable method which will produce such a heatedliquid mixture is one wherein a polyhalo-substituted aromatic compoundis contacted under suitable polymerization conditions with reactantscomprising a sulfur source, a polar organic compound and water, toproduce a polymerization reaction mixture. Depending upon the type ofpolymer prepared, this reaction mixture can be either (a) a liquidmixture, comprising a particulate PAS resin in a liquid phase, a polarorganic compound, water, unreacted monomer and various liquid by-productmaterials; or (b) a slurry, wherein the solid component thereofcomprises a particulate PAS resin, and wherein the liquid componentthereof comprises a polar organic compound, water, unreacted monomer andvarious liquid by-product materials.

When practicing the second embodiment of this invention, if the heatedliquid mixture is prepared from a completed PAS polymerization process,and further if the reaction mixture of this completed polymerizationprocess is a slurry wherein the solid component thereof comprises aparticulate PAS resin, the temperature of this slurry must be elevatedto a point above the solid-to-liquid phase transitional temperature ofthe particulate PAS resin contained therein. Under these conditions, aliquid mixture results. This liquid mixture comprises the firstparticulate PAS resin in a liquid phase, a polar organic compound,unreacted monomer and various liquid by-product materials.

Another example of a suitable method which results in such a heatedliquid mixture comprises taking a particulate PAS resin which hasalready been prepared, recovered, and optionally dried, and adding thisparticulate resin to a liquid mixture comprising a polar organiccompound to form a slurry. This slurry is then heated to a temperaturewhich is at or above the solid-to-liquid phase transitional temperatureof the first particulate resin contained therein.

The time for which the heated liquid mixture should be held above thissolid-to-liquid phase transitional temperature depends, in part, on thetemperature employed, and the concentration of the higher molecularweight PAS resin in the first particulate PAS resin. The hold period ofthe liquid mixture at or above the solid-to-liquid phase transitionaltemperature generally ranges from about 5 seconds to about 8 hours,preferably from about 10 seconds to about 4 hours.

In the heated liquid mixture employed in the second embodiment of thisinvention, the molar ratio of the moles of polar organic compound permoles of first particulate PAS resin is generally determined bymechanical and/or economic limitations and can readily be determined byone of ordinary skill in the art without undue experimentation.

The polar organic compounds useful when practicing the second embodimentof this invention are the same as those useful when practicing the firstembodiment of this invention. The presently preferred polar organiccompound for practicing the second embodiment of this invention is NMP.

If treating the PAS resin in accordance with the second embodiment ofthis invention, after the heated liquid mixture is prepared, the heatedliquid mixture is slowly cooled to a temperature in the range of about20° C. (68° F.) to about 40° C. (104° F.) below the liquid-to-solidphase transitional temperature of the liquid-phase, first particulatePAS resin contained therein, to form a first slurry wherein the solidcomponent thereof comprises a second particulate PAS resin, and whereinthe liquid component thereof comprises the polar organic compound.

The term "slow cooling" is meant to imply that no external means areapplied to reduce the temperature of the reactor contents. The contentsare allowed to cool by removing all heating means from the reactor.Generally, this slow cooling of the heated liquid mixture occurs at arate less than about 1° C. (1.8° F.)/minute.

The time for which the first slurry should be held within thetemperature range set out above depends in part on the treatingtemperature employed, the concentration of the lower molecular weightPAS resin in the first particulate PAS resin, and the desiredconcentration of lower molecular weight PAS resin in the novelparticulate high molecular weight PAS resin. The hold period of thefirst slurry at the appropriate temperature range generally ranges fromabout 5 seconds to about 8 hours, preferably, from about 10 seconds toabout 4 hours.

After the heated liquid mixture has been cooled to the appropriatetemperature to form the first slurry and held at that temperature for anappropriate period of time, the temperature of the first slurry israpidly lowered to a temperature of about 50° C. (122° F.) below theliquid-to-solid phase transitional temperature of the first particulateresin. Preferably, the temperature of this first slurry is rapidlylowered to a temperature of about 75° C. (167° F.) below theliquid-to-solid phase transitional temperature of the first particulateresin.

The rapid lowering of temperature is achieved as previously describedfor the first embodiment. The rate at which the temperature of the firstslurry is reduced during the rapid lowering is generally greater thanabout 1° C. (1.8° F.)/minute.

The rapid cooling of the heated first slurry to a temperature of about50° C. (122° F.) below the liquid-to-solid phase transitionaltemperature of the first particulate resin contained therein results inthe formation of a second slurry, wherein the liquid component thereofcomprises a polar organic compound and wherein the solid componentthereof comprises a third particulate polymeric mixture comprising anovel particulate high molecular weight PAS resin and a minor amount ofparticulate low molecular weight PAS resin.

Because of the difference in particle size of the low molecular weightand high molecular weight PAS resins present in the particulatepolymeric mixture produced, the high molecular weight resin can beseparated from the low molecular weight resin by, for example,filtration through an appropriately chosen filtration means.

The novel particulate high molecular weight PAS resin prepared inaccordance with the second embodiment of the invention has a highermolecular weight than its respective first particulate PAS resin wouldif recovered by conventional means. The low molecular weight PAS resinresulting from this second embodiment of the invention has a lowermolecular weight than the first particulate PAS resin would if recoveredby conventional means.

EXAMPLES

The following are examples illustrating the process of the presentinvention. Particular materials employed, species, and conditions areintended to be further illustrative of this invention and are not meantto limit the reasonable scope thereof.

EXAMPLE I

This example illustrates the operation of the first embodiment of thisinvention in which the first slurry is heated to a temperature in therange of about 20° C. to about 40° C. below the liquid-to-solid phasetransitional temperature of the first particulate PAS resin in the polarorganic compound.

To a one gallon stirred reactor was charged 1000 cc ofN-methyl-2pyrrolidone (NMP) and 100 grams of a PPS polymer preparedusing techniques disclosed in U.S. Pat. No. 3,919,177 and exhibiting aflow rate with smoking, of 18 g./10 min. (determined as indicated inTable I). The reactor was purged with nitrogen and sealed at atmosphericpressure. The reactor was heated to 200° C. and held there for one hour.Heating was then terminated, 500 cc of NMP at room temperature wasrapidly added and the reactor was rapidly cooled to about roomtemperature by passing cold water through the cooling coils of thereactor. Opening the reactor revealed uniform granular particles whichwere recovered on a 100 mesh screen. The recovered and dried particleshad a total mass of 91.5 grams, representing 91.5 weight percent of thepolymer originally charged. The recovered polymer exhibited a flow rateof 6 g./10 min., with no smoking. The recovered polymer is hereinafterreferred to as Resin 1.

To further illustrate the operation of the first embodiment of thisinvention, six additional resins were prepared using essentially thesame technique as described for Resin 1 above. The results of thesepreparations as well as notations of variations from the procedure usedfor Resin 1 are contained in Table I, with the resins designated asResins 2-7.

                                      TABLE I                                     __________________________________________________________________________        Original                                                                            Flow Rate                                                                              Granular                                                                             Liquid                                                                            Treatment                                       Resin                                                                             Flow Rate.sup.a                                                                     After Treatment                                                                        Yield, wt. %                                                                         Added                                                                             Temperature, °C.                         __________________________________________________________________________    1   18    6        91.5   NMP 200                                             2   18    3.5      71.5   NMP 210                                             3   18    6.8      93.8   NMP 190                                             4   18    3.6      91.4   Water                                                                             200                                             5   75    56       93.2   Water                                                                             200                                             6   75    52       84.9   Water                                                                             210                                             7   138   78       94.4   NMP 200                                             __________________________________________________________________________     .sup.a Flow rate, in g/10 min., of starting polymer, before treatment, as     determined by ASTM D1238, Procedure B, condition 315/5.0, modified in tha     the initial preheat time used was five minutes rather than the six minute     minimum specified by the test method.                                    

In all cases of Example I, the product polymer had a lower flow ratethan that of the starting polymer, demonstrating that the inventiveprocess produced a polymer of higher molecular weight that that of thestarting polymer.

EXAMPLE II

This example illustrates the operation of the second embodiment of thisinvention in which the first slurry is heated to a temperature above theliquid to solid phase transitional temperature of the first particulatePAS resin in the polar organic compound.

To a one gallon stirred reactor was charged 2000 grams of a PPS polymerslurry prepared using techniques described in U.S. Pat. No. 3,919,177and exhibiting a flow rate of 75 g./10 min. (determined as indicated inTable II), 20 cc of water and 300 cc of N-methyl-2-pyrrolidone (NMP).The reactor was purged with nitrogen and sealed at atmospheric pressure.The reactor was heated to 260° C. and held there for ten minutes.Heating was then terminated and the reactor was cooled slowly to 200° C.Upon reaching this temperature, 500 cc of NMP at room temperature wasrapidly added to the reactor and the reactor was rapidly cooled to aboutroom temperature by passing cold water through the cooling coils of thereactor. Opening the reactor revealed uniform granular particles whichwere recovered on a 100 mesh screen. The recovered and dried particleshad a mass of 322.8 grams, representing 16.1 weight percent of thepolymer originally charged. The recovered polymer exhibited a flow rateof 60.5 g./ 10 min. The recovered polymer is hereinafter referred to asResin 8.

To further illustrate the operation of the second embodiment of thisinvention, two additional resins were prepared using essentially thesame technique as described for Resin 8 above. The results of thesepreparations, as well as notations of variations from the procedure usedfor Resin 8, are contained in Table II, with the resins designated asResins 9 and 10.

                                      TABLE II                                    __________________________________________________________________________        Original                                                                            Flow Rate                                                                              Granular                                                                             Quench                                                                             Treatment                                      Resin                                                                             Flow Rate.sup.a                                                                     After Treatment                                                                        Yield, wt %                                                                          Liquid                                                                             Temperature, °C.                        __________________________________________________________________________    8   75    60.5     16.1   NMP  260                                            9   75    54.3     16.1   water                                                                              260                                            10  75    57.4     15.8   water                                                                              260                                            __________________________________________________________________________     .sup.a Flow rate, in g/10 min., of starting polymer, before treatment, as     determined by ASTM D1238, Procedure B, condition 315/5.0, modified in tha     the initial preheat time used was five minutes rather than the six minute     minimum specified by the test method.                                    

In all cases of Example 2, the product polymer has a lower flow ratethan that of the starting polymer, demonstrating that the inventiveprocess produces a polymer of higher molecular weight that that of thestarting polymer.

Although, this invention has been described in detail for purposes ofillustration, it is not to construed as limited thereby, but is intendedto cover all changes and modification within the spirit and scopethereof.

What is claimed is:
 1. A process for preparing a particulate highmolecular weight poly(arylene sulfide) resin comprising the steps of:(a)preparing a heated liquid mixture comprising a first particulatepoly(arylene sulfide) resin in a liquid phase and a polar organiccompound wherein the temperature of said liquid mixture is above thesolid-to-liquid phase transitional temperature of said first particulatepoly(arylene sulfide) resin, (b) slowly cooling said heated liquidmixture to a temperature of about 20° C. to about 40° C. below theliquid-to-solid phase transitional temperature of said first particulatepoly(arylene sulfide) resin in said polar organic compound to form afirst slurry comprising a liquid component and a solid component,wherein the liquid component of said first slurry comprises said polarorganic compound and wherein the solid component of said first slurrycomprises a second particulate high molecular weight poly(arylenesulfide) resin, and (c) rapidly cooling said first slurry to atemperature of about 50° C. below said liquid-to-solid phasetransitional temperature of said first particulate poly(arylene sulfide)resin, to form a second slurry comprising a liquid component and a solidcomponent, wherein the liquid component of said second slurry comprisessaid polar organic compound, and wherein the solid component of saidsecond slurry comprises a particulate polymeric mixture comprising athird particulate high molecular weight poly(arylene sulfide) resinhaving a higher molecular weight than its respective first and secondparticulate resins would when recovered by conventional means.
 2. Aprocess according to claim 1 wherein said rapid cooling is at a rategreater than about 1° C./minute.
 3. A process according to claim 1wherein said slow cooling takes place at a rate of less than 1°C./minute.
 4. A process according to claim 1 wherein said poly(arylenesulfide) resin is selected from the group consisting of poly(arylenesulfide)s, poly(arylene sulfide sulfone)s, poly(arylene sulfideketone)s, poly(arylene sulfide diketone)s and poly(biarylene sulfide)s.5. A process according to claim 1 wherein said poly(arylene sulfide)resin is poly(phenylene sulfide).
 6. A process according to claim 4wherein said poly(arylene sulfide) resin is a poly(arylene sulfidesulfone).
 7. A process according to claim 4 wherein said poly(arylenesulfide) resin is a poly(arylene sulfide ketone).
 8. A process accordingto claim 4 wherein said first slurry is prepared by contacting apolyhaloaromatic compound with a sulfur source and a polar organiccompound under polymerization conditions.
 9. A process according toclaim 1 wherein said liquid component of said first slurry furthercomprises water.
 10. A process according to claim 8 wherein said firstslurry is prepared by adding an already recovered poly(arylene sulfide)resin to a liquid mixture comprising a polar organic compound.
 11. Aprocess according to claim 1 wherein said polar organic compound isN-methyl-2-pyrrolidone.